The invention relates to sortation conveying systems used to fulfill orders of assorted rectangular items such as books, packaged software, compact discs, games, video cassettes, etc. In particular, the invention relates to an inductor apparatus that loads items into assigned pockets on a core conveyor for the sortation system in single file with each item. standing upright on edge in an essentially vertical orientation, thus facilitating efficient downstream processing and sorting.
In centralized distribution applications, order fulfillment is often accomplished using computer controlled sortation conveying systems. Such systems can sometimes have lengths approaching 300 feet. Quite often, it is desirable that the sortation system be capable of fulfilling orders of intermingled items having assorted sizes. For example, it is not uncommon for an order to require a selected number of books having assorted sizes, intermingled with video cassette containers, compact disc containers, software, or the like.
In sortation conveying systems, a core conveyor conveys assorted items in single file, preferably in an upright position standing on edge so that bar code readers can easily identify the item prior to subsequent sorting and processing downstream. One type of core conveyor has separators or cleats dividing the conveyor belt into individual pockets. Sortation conveying systems normally include several inductor stations that are coordinated with the core conveyor to supply items to the pockets on the core conveyor in an organized manner. The items within the pockets on the core conveyor are then processed, sorted and stacked into separate outgoing orders. It is not unusual for outgoing orders to consist of hundreds of intermingled items, each generally having a rectangular shape but unique dimensions.
This invention relates to improvements to the operation of the inductor stations that load the items onto the core conveyor. It is desirable that workers be able to load assorted items into the inductor station in an easy and efficient manner, and that the inductor station be able to have items continually ready for loading onto the core conveyor under normal operating conditions. Preferably, the items should be standing upright on edge as the items are loaded onto the core conveyor. It is also desirable that the inductor stations be capable of efficiently handling assorted items having various dimensions.
The invention provides an inductor station that is able to accept charges of assorted items at an inconsistent or sporadic rate, yet is designed to continuously provide individual items ready for loading into assigned pockets in the core conveyor. In its preferred configuration, the inductor station accepts an assortment of substantially rectangular items each standing upright on edge and grouped in series side-by-side with other items. Each group of assorted items loaded into the inductor station is referred to as a charge. Each charge of assorted items is conveyed into a feeder tray for the inductor station in sequence one charge at a time, preferably using a gravity feed ramp with retractable queuing plates. A feeding assembly feeds the charge of assorted items along the feeder tray to a loading mechanism located at a discharge end of the feeder tray. The loading mechanism strips the endmost item from the charge, and loads the item onto a takeaway transporter with the item standing upright on edge. The loading mechanism is controlled in sync with the core conveyor to load the respective item into an assigned pocket on the core conveyor. Preferably, this is accomplished using a computer-controlled indexing motion stripping conveyor to load the items from the. charge on the feeder tray in single file onto the takeaway transporter. In one embodiment of the invention, the takeaway transporter is a takeaway conveyor belt. In another embodiment of the invention, the takeaway transporter is a transport chute.
The invention is particularly efficient and reliable because each respective item is loaded into the inductor station standing upright on edge, and maintains an upright on edge orientation as it passes through the inductor station and into the assigned pocket on the core conveyor. Maintaining consistent upright on-edge orientation allows for effective continued alignment of items being processed through the inductor station, and therefore reduces the risk of misfeeds and enhances throughput.
In the preferred embodiments of the invention, the feeding assembly, which feeds the assorted items along the feeder tray to the loading mechanism, includes two pushing mechanisms: namely, a main pushing mechanism and a secondary pushing mechanism. The operation of the main pushing mechanism and the secondary pushing mechanism are coordinated electronically to facilitate substantially continuous feeding of assorted items to the loading mechanism. More specifically, the main pushing mechanism uses a pushing hand mounted for travel along the feeder tray between a home location and a stop location for the main pushing mechanism. The home location for the main pushing mechanism is located on the side of the feeder tray opposite the discharge end of the feeder tray. The main pushing mechanism is positioned at its home location when the feeder tray is ready to receive the next charge of assorted items. The main pushing mechanism then applies pressure against the charge to move the charge of assorted items along the feeder tray to the loading mechanism at the discharge end of the feeder tray. As mentioned, the endmost item in the charge is loaded onto the loading mechanism. In order to facilitate appropriate cooperation between the pushing mechanism and the loading mechanism, the pushing mechanism pushes in a controlled pulsating manner such that the pushing pressure is relieved when the endmost item is loaded from the feeder tray onto the loading mechanism. The pushing pressure is reapplied after the endmost item has been loaded onto the takeaway conveyor and the loading mechanism is ready to be loaded with the next item in the charge. The controlled pulsating action is preferred because it is desirable to relax the tension in the charge after the endmost item is loaded into the loading mechanism in order to reduce frictional and normal forces operating between the endmost item and the next item in the charge. The relaxation improves the reliability of the loading mechanism and helps to prevent misalignment and misfeeds. The secondary pushing mechanism has a retractable pushing hand that is mounted for travel along the feeder tray between a home location for the secondary pushing mechanism and the discharge end of the feeder tray. The home location for the secondary pushing mechanism is located between the. home location for the main pushing mechanism and the discharge end of the feeder tray, and preferably substantially closer to the discharge end of the feeder tray. As the main pushing mechanism moves the charge along the feeder tray and becomes close to the discharge end of the feeder tray, the secondary pushing mechanism is implemented as a substitute for the main pushing mechanism. After substitution, the main pushing mechanism returns to its home location ready to accept the next charge of assorted items while the secondary pushing mechanism continues to feed the remainder of the charge to the loading mechanism. The pushing hand for the secondary pushing mechanism retracts for travel under the floor of the feeder tray as it returns towards its home position prior to substitution for the main pushing mechanism, thus avoiding interference with assorted items in the feeder tray as it returns. When it is time for the secondary pushing mechanism to substitute for the main pushing mechanism, the fingers on the pushing hand for the secondary pushing mechanism extend upward through slots in the feeder tray and into openings in the hand for the main pushing mechanism. The secondary pushing mechanism then continues to feed the charge towards the loading mechanism, and the main pushing mechanism returns to its home position in order to receive the next charge of assorted items.
In another embodiment, the feeding assembly uses a stabilizing hand to prevent the endmost items from tipping in the feeder tray. The stabilizing hand is preferably mounted for travel along the feeder tray between the home location for the secondary pushing mechanism and the discharge end of the feeder tray. The stabilizing hand is retractable, like the hand for the secondary pushing mechanism. While movement of the main pushing mechanism and movement of the secondary pushing mechanism are independently powered and controlled for coordinated operation (preferably using pneumatic controls to slide the mechanisms along the linear bearings), the movement of the stabilizing hand is not powered. Rather, the stabilizing hand travels towards the discharge end of the feeder tray when it is pushed by a charge of assorted items being pushed by the main pushing mechanism. In this manner, the stabilizing hand prevents the endmost item in the charge from tipping in the feeder tray. When the stabilizing hand approaches the remaining portion of the previous charge on the loading mechanism, the stabilizing hand retracts. The stabilizing hand then returns to its home position, which is the home position for the secondary pushing mechanism, when it is pushed by the retracted secondary pushing mechanism returning to its home position. Preferably, separate pneumatic lifts control the retraction of the pushing hand for the secondary pushing mechanism and the retraction of the stabilizing hand, although it is preferred that these pneumatic lifts be operated in unison. In this embodiment, the openings in the hand of the main pushing mechanism should be sufficiently large to accommodate both the fingers on the pushing hand for the secondary pushing mechanism and the fingers on the stabilizing hand.
The preferred loading mechanism is designed to ensure that only the endmost item from the charge of assorted items on the feeder tray is loaded onto the takeaway transporter per each loading cycle. This sometimes can be difficult because friction between adjacent items within the group is often significant, especially when boxed items are wrapped in film. The preferred loading mechanism overcomes the friction attraction forces and substantially reduces the probability of misfeeds and misalignment. The loading mechanism comprises a lift to lift the endmost item of the charge. A substantially vertical guide plate is located adjacent the lift and substantially perpendicular to the feeder tray. A vertical stripping conveyor is located adjacent the guide plate on the side opposite the lift. The stripping conveyor has cleats extending from the conveyor beyond the guide plate in the direction of the lift. The stripping conveyor is preferably an indexing motion stripping conveyor which is computer-controlled to coordinate operation with the core conveyor. The feeding assembly pushes the endmost item against the guide plate and onto the lift. The item on the lift is lifted and then the stripping conveyor indexes forward to push the item onto the takeaway transporter.
The lift is preferably a pivotally mounted lever and has an actuation arm for moving the lever between a lowered position and a raised position. The top surface of the lever preferably has a width that is less than the width of assorted items fed to the lift, thereby ensuring that it lifts only the endmost item in the charge on the feeder tray. The loading mechanism also preferably includes a holdback member that is located between the lift and the takeaway transporter. The holdback member is a rail or some other object defining a horizontal obstacle for items lying in the feeder tray immediately upstream of the infeed to the takeaway transporter. The height of the horizontal obstacle is preferably no higher than the loading height for the takeaway transporter. When the endmost item is loaded onto the takeaway transporter, the holdback member holds subsequent items in the charge in place within the feeder tray even if there is significant frictional attraction between adjacent items. The lift raises the endmost item so that the lower edge of the item is raised at least as high as the loading height of the takeaway transporter and above the horizontal obstacle of the holdback member, and at the appropriate time the stripping conveyor pushes the item onto the takeaway transporter.
Various other features and advantages of the invention should be apparent to those skilled in the art upon inspecting the drawings and the following description thereof. For example, the invention uses various sensors and control techniques which are particularly effective for maintaining continued reliability as well as various other features.